A. Field of the Invention
The present invention generally relates to refrigeration systems and, more particularly, to a thermostat control capable of providing multiple temperature ranges in a single refrigeration compartment.
B. Description of the Prior Art
Rotatable controls for controlling the operation of many different devices, including temperature controlling thermostats, are old and well-known in the prior art as exemplified by U.S. Pat. Nos. 1,017,224; 1,423,627; 1,689,236; 2,684,811; 3,019,667; 3,564,929; 3,690,287; 3,999,158; and 4,014,178. The '224 patent relates to a feed indicator for a valve that enables the valve to be opened a predetermined amount and prevents its opening beyond that predetermined amount. The '627 patent relates to an indicator and movable stop for a valve to control the flow of fuel to the burner of a stove. The '236 patent also discloses an indicator and adjustable stop for use in controlling the operation of a rotary valve. The '811 patent relates to a rotatably adjustable temperature regulating thermostat for cooking appliances and includes an axially movable, depressable button that automatically reduces the temperature setting of the control dial of the thermostat by a fixed amount, for example, by 75.degree. F.
The '667 patent relates to a rotatable control knob for electronic equipment that includes a spring biased locking mechanism that is ineffective when the control knob is rotated from an "off" position to one of several "on" or energized positions; the mechanism, however, prevents the unintentional or accidental rotation of the control knob to the "off" position. The '929 patent relates to a mechanical arrangement for limiting the rotation of a shaft, for example, a rotary control shaft of a control mechanism for controlling the audio volume in a television or radio receiver. In the '929 patent, the control shaft includes an abutment that contacts an adjustable abutment to limit the rotation of the control shaft.
The '287 patent relates to a multiturn rotary switch in which a movable indicator is attached to an axially and rotatably movable control knob. The '158 patent relates to a range limiter for a thermostat, for example, a thermostat for controlling the temperature of a room, in which desired upper and lower temperature limits can be easily changed by the owner of a rented or leased facility but cannot be as easily changed by the occupant of that room. Finally, the '178 patent discloses a refrigerator having multiple refrigeration compartments and rotatable thermostat control dials for controlling the temperature within each of the multiple refrigeration compartments.
While many control schemes exist in the prior art for controlling the operation of diverse devices within desired ranges, a need exists for a single thermostat control capable of providing multiple, preferably non-overlapping, temperature ranges in a single refrigeration compartment to thereby enable a refrigeration unit to be selectively used as a freezer or as a refrigerator or as a wine cooler.